Screening of novel plants for biogas production in northern conditions

The objective of this study was to screen nine annual or perennial novel plants for biogas production cultivated in years 2007–2010 in Finland. The most promising novel plants for biogas production were found to be brown knapweed, giant goldenrod and Japanese millet producing 14–27 t total solids/ha and 4000–6100 Nm3 CH4/ha. The specific methane yields of all studied plants varied from 170 to 381 Nm3 CH4/t volatile solids (VS), depending on harvest time and plant species. Co-digestion of brown knapweed with cow manure in continuously stirred tank reactor was investigated and the highest methane yield was 254 NL CH4/kg VS, when the share of brown knapweed was 50% in the feed VS (organic loading rate (OLR) 2 kg VS/m3/d). The cultivation managements and sustainability of novel plants for biogas production have to be investigated.